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CAT 257B3 electrical - Front door safety

F

Fairfieldcounty

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Jul 29, 2015
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I have a 2011 257B3, everything works when the dummy/jumper plug for the front window is plugged in. Once I plug in the connector for the door, nothing works as if its not plugged in ( no hydraulics, wiper etc) no broken wires behind door cover, everything seems to be intact. Any ideas on where to start would be appreciated, Fuses are good, not sure if theres a relay or not or which it would be. is there a safety switch that I can check, my 246C has one on the door but I don't see one on this machine. Serial number is B7H00466 if that helps. Thank you in advance.
 
D

DIYDAVE

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MD
I'd start with the connector, then check ground(s), and wiper motor (if so equipped) to see if there's a dead short...
 
F

Fairfieldcounty

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Ive checked the grounds and wiring yesterday, everything checked out okay. The plug is intact, pins are good.
 
T

The Peej

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Feb 6, 2012
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Connecticut
I'm not familiar with that machine but there has to be a switch that is telling the machine the door is open. It could be part of the door latch but its there somewhere. let us know what you find
 
mitch504

mitch504

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If everything works with the dummy plugged in, but not with the door plugged in instead, the problem has to be outboard of that plug. Nothing changes at the fuses or relays, or on the machine itself. Like peej says, if you don't see the door switch, it's probably in the latch.
 
mitch504

mitch504

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If everything works with the dummy plugged in, but not with the door plugged in instead, the problem has to be outboard of that plug. Nothing changes at the fuses or relays, or on the machine itself. Like peej says, if you don't see the door switch, it's probably in the latch.
 
kshansen

kshansen

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Retired Mechanic in Stone Quarry
Well I looked up in SIS and there is a "limit switch" that is part of the door assembly.

229-8757 SWITCH AS-LIMIT (ENGINE START, HYD LOCKOUT)

In parts break down it looks to be at the lower left corner of the door as you sit in the operators seat. That or the wirng to I would be the first place I would be looking!

Maybe with a complete S/N I could see if the wiring schematics are of any help.
 
F

Fairfieldcounty

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Jul 29, 2015
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CT
thanks for the reply, I have checked wiring, fuses etc. I am going to try replacing the switch on Monday. I thought maybe the switch wasn't getting a good connection since I painted the door frame with rustoleum but I ground it down today and tried with no luck. The serial number I provided is what I have, if theres is more information I can provide please let me know and I will get it. I appreciate the time and help you guys have put forth thus far. Im hoping changing that switch out will solve my issue. I gave this machine to a buddy for winter and his guys smashed the glass, replaced it and all of a sudden no wiper, hydraulics etc. (thats what I get but at least I'm getting paid for it)
 
Cmark

Cmark

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Here's a schematic for the door. If you lose wipers, washers and lockout when you plug it in, it seems almost certain that you have lost your ground. (200 Black). BTW, the jumper plug connects pins 2 and 4 of conn 7.

257B3_Door.png
 
kshansen

kshansen

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mitch504 said:
You're getting slack, Ken. The serial number in his post isn't right?
Click to expand...
Dang! and I was not replying late at night or before coffee in the morning! Guess I need a "Dope Slap" for that one!

At least Cmark appears to not have dropped the ball!

Should be easy to check for good ground and also the action of the switch before just buying a new switch and then find out the problem was a broken wire.
 
F

Fairfieldcounty

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CT
Update: pulled it all back apart, checked all wiring, no pinches or breaks found or loose connections. Pulled out the test light and checked fo power in wiring while plugged in and machine on -no power. wiper pump is working leading me to believe the ground is good. thoughts?
 
Cmark

Cmark

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If the washer pump is working, you at least have a ground as far as connector 12.

Not knowing your electrical skill level, I'll try and step it through, bearing in mind you say the machine starts with the cab door jumper plug in place.

  1. Check for ground at the lockout switch. Connect the clip on your test light to battery +, unplug the lockout switch and probe the pin A, black 200 wire. The light should come on. If not, you have an open circuit in the black wire between the lockout switch plug and the door plug Conn 7.
  2. At the lockout switch harness plug, bridge together pins A, black 200 and B, white E917. Try and start the machine. If it won't start, you have an open circuit in the white wire between the lockout switch plug and the door plug Conn 7.
  3. If it does start, there is a problem with the lockout switch. If the door has taken a hit, it may be out of adjustment. Plug it back in and close the door. Take a screwdriver with you and make sure the plunger is pushed all the way in while you try to start it.
 
F

Fairfieldcounty

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CT
I have ground at the lockout switch, and the wiper motor. I did the procedure as you stated and the machine started and operated as it should so I need to replace the lockout switch. Wiper still doesn't work. Is it the same procedure to test the wiper motor? Im assuming thats no good.
Thank you all for the help. Much appreciated
 
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